Apparatus for cleaning interior surfaces of pipe strings



Dec. 25, 1962 A. R. HILTON, JR., ETAL 3,070,169

APPARATUS FOR CLEANING INTERIOR SURFACES OF PIPE STRINGS Filed Nov. 29,1961 INVENTORS.

ALBERT R.HILTON,JR. g:QORACE H. SPAIN,

ATTORNEY.

FIG. 2.

Bfillldfi Patented Dec. 25, 1962 3,070,169 APPARATUS F0. CLEANINGINTERIOR SURFACES 9F PIPE STRINGS:

Albert R. Hilton, Jr., Richardson, and Horace H. Spain, Houston, Tex.,assignors, by mesne assignments, to Jersey Production Research Company,Tulsa, Okla, a corporation of Delaware Filed Nov. 29, 1961, Ser. No.155,549 3 Clairns. (Cl. 166-17'7) This invention relates to apparatusfor cleaning the interiors of elongated pipe strings such as are used inwell installations.

There are many techniques in common use in oil field technology thatrequire the removal from pipe string walls of fluid films or dropletsthat remain after fluids have been flowed or pumped through the pipestrings. For example, in connection with consolidation of unconsolidatedor sandy earth formations surrounding a well bore, it has become thepractice to pump through pipe strings into the formation fluids whichact to bind together the earth particles making up the formation whilemaintaining acceptable earth formation porosity. If the fluids used forformation consolidation were allowed to remain clinging to the interiorWalls of the pipe string for an appreciable amount of time after theoperation has been completed, the liquids would harden and would impedelater well operations. Therefore, it is desirable to clean the interiorsurfaces of the pipe strings, using a device such as a wiper plug, assoon as possible after such liquid materials have been passedtherethrough.

Often there arises a need for cleaning the Wall of a well pipe stringhaving an interior diameter that changes at some point along its length.For example, it is common practice to temporarily lengthen a tubingstring by lowering a small diameter extension pipe through the tubingstring previously in place in the well bore and to land the upper end ofthe extension pipe in a landing or seating nipple permanently installedat the lower end of the regular tubing. Manifestly, any wiper plug ofsufficiently large diameter to clean the interior surface of the upperpipe string will not enter the extension pipe, and any plug small enoughto enter the extension pipe will not wipe the Walls of the larger upperpipe string.

In accordance with the teachings of the present invention, there isprovided an elongated body member having a bore extending therethroughand having mounted on the outer surface thereof annular resilient wipingmeans having an outside diameter slightly greater than the insidediameter of an upper section of well pipe to be cleaned. An elongatedmandrel is provided having at least a portion of its length turned to anoutside diameter no larger than the diameter of the bore through thebody member so that the portion of the elongated mandrel can fit intosaid bore. Resilient wiping means affixed to the outer surface of themandrel have an outside diameter at least as great as the insidediameter of the lower extension pipe for wiping engagement therewith.The enlongated mandrel is releasably held within the bore of theelongated body member so as to be disconnected from the body member whenpressure of predeterminable magnitude is exerted thereon. Thus, the bodymember and mandrel may be pumped down the upper pipe string until theextension pipe is reached. The mandrel will slip into the bore of theextension pipe, will become disconnected from the body member by thesimple procedure of exerting hydraulic pressure thereon, and will beoperative to wipe clean the interior surface of the extension pipe.

It is also within the ambit of the present invention to provide a checkvalve in the bore of the body member above the elongated mandreloperative to oppose fluid flow upwardly through the body member, and toprovide a shear pin extending through a port in the body member toengage the elongated mandrel for releasably connecting together the bodymember and mandrel. The function of the check valve means is to permitretrieval of the body member from the upper pipe string section by thesimple operation of pumping fluids down the annulus around the upperpipe string and up the bore of the pipe extension and upper pipe string.

Objects and features of the invention which are not apparent from theabove discussion will become evident upon consideration of the followingdescription thereof taken in connection with the accompanying drawing,wherein:

FIG. 1 is a sectional view illustrating a preferred embodiment of theinvention;

FIG. 2 is a cross-sectional View taken along section 2-2 of FIG. 1; and

FIG. 3 is a schematic view of a well installation utilizing theapparatus of FIG. 1 for the purpose of illustrating the utility of theinvention.

With reference now to FIG. 1, there is illustrated an elongated annularbody member 1 having a flanged section '7 at the lower end thereof andprovided with interior and exterior threads at the upper end thereof.There is also provided a small opening 16 between the exterior of thebody section and its bore for receiving a shear pin, for purposes to bedescribed below. As illustrated, the bore through the body member 1extends the entire length thereof and is of substantially uniformdiameter from the lower end of the body member 1 to a point slightlyabove the opening 16.

A plurality of resilient annular wiping members 5, which may be of arubber-like material such as neoprene, are aihxed to the outer surfaceof the body member 1 and are spaced apart by annular spacers or Washers3. The spacers 3 and Wiping members 5 are held on the exterior of thebody member 1 above flange 7 by a retaining nut 9 screw-threaded ontothe external threads at the upper end of the body member 1. The outsidediameter of the wiping members 5 is slightly greater than the insidediameter of a pipe to be cleaned thereby so as to be in wipingengagement with the pipe.

A check valve housing 11 is inserted into the bore of body member 1 atthe upper end of the body member and is provided with threads to engagethe interior threads within the bore of the body member. Within thecheck valve housing 11 is provided a conventional ball valve member 13held against a tapered seating sur face within the bore of the housing11 by a coil spring 15. Such apparatus is well known in the art and willnot not be further discussed herein. The function of the check valve isto oppose fluid fiow upwardly through the bore of body member 1 whilepermitting fluid flow down through the body member upon exertion thereonof sufiicient pressure to overcome the force of spring 15.

An elongated mandrel 23 is provided having an upper portion adapted toslide into the bore of body member 1. The mandrel 23 has a reducedsection 2-1 at the upper end thereof so as to receive a shear pin 17slidable through opening 16 for releasably connecting together themandrel and the body member. This construction is most perspicuouslyillustrated in FIG. 2. The lower portion 25 of the mandrel has afiixedthereto a plurality of wiper members 27 spaced apart by spacers 29. Thelower mandrel portion 25 has a reduced diameter so asto provide ashoulder for retaining the spacers 29 and Wiping members 27 on themandrel. A pointed retaining nut 31 is screwed on the lower end ofmandrel portion 25 to hold the spacers 29 and wiping members 27 on themandrel portion 25. The pointed tip on nut 31 is desirable so that theapparatus may be easily insertable into the lower extension pipe 43, tobe described below. The outside diameter of wiping members 27 isslightly larger than the inside diameter of the lower extension pipe tobe wiped clean thereby.

With reference now to FIG. 3, the utility of the apparatus describedwith reference to FIG. l and FIG. 2 is readily observed. In FIG. 3 thereis illustrated a conventional permanent completion type wellinstallation comprising a casing string 33 cemented to surrounding earthformations, an upper tubing string 35 coextending with casing string 33from well head apparatus (not illustrated) at the earths surface, and atubing extension 43 of smaller diameter than tubing string 35. Thetubing string 35 is provided with a landing nipple 37 at the lower endthereof. The tubing extension 43 is provided With a radially extensiblehanger mechanism 39 adapted to seat in landing nipple 37, and with aresilient packing 41 for conventional isolation purposes. The wiperassembly illustrated in FIG. 1 is driven down the tubing string 35 byliquid or gas pumped into the tubing string behind the assembly. Whilethe assembly is being driven down the tubing string, the check valve inthe bore of body member 1 will remain closed. Liquid adhering to theinterior surface of tubing string 35 as a result of previous welltreating operations will be wiped down the tubing by wiping members 5.When the assembly reaches the upper end of tubing extension 43, mandrelwill enter the tubing extension. The hydraulic or pneumatic drivingpressure is thereupon increased to open the check valve so that pressureis exerted on the upper end of mandrel 23 to shear the shear pin 17. Themandrel will thereupon be driven through the tubing extension 43 to wipeclean the interior surface of the tubing string. The mandrel is ejectedfrom the lower end of tubing extension 43 and allowed to fall to thebottom of the well. If desired, the mandrel 23 and spacer members 29 maybe constructed of aluminum so that they may be dissolved by spotting acaustic or acidic liquid at the bottom of the well, which liquidthereafter may be circulated out of the well.

To remove the body member I from the tubing it is necessary only toreverse circulation of liquids so as to force the body member up thetubing string. If desired, however, a retrieving head or neck 8, shownin dotted lines, may be integrally formed with coupling nut 9 so that aconventional wireline retrieving apparatus may be used to pull the bodymember and its associated apparatus out of the tubing string.

The invention is not to be restricted to the specific structural detailsor arrangement of parts herein set forth, as various modificationsthereof may be effected without departing from the spirit and scope ofthis in vention.

Objects and features of the invention having been completely described,what we wish to claim is:

1. For use in a well installation including a well pipe having an uppersection with a first inside diameter, and a lower section with a secondsmaller inside diameter, a pipe wiper comprising:

an elongated body member having a bore extending therethrough, andincluding an outwardy extending flange at one end thereof, the diameterof said bore being less than the inside diameter of said lower section;

:a check valve at the upper end of said bore for opposing passage offluids up through said bore;

first annular resilient wiping means carried by said body member abovesaid flange, said wiping members having an outside diameter slightlygreater than the inside diameter of said upper section of said wellpipe;

annular spacing means on said body member between said wiping members;

tit

a retaining nut afiixed to said body member at the opposite end fromsaid flange to hold said wiping members and said spacing means on saidbody memher;

an elongated mandrel having at least a portion thereof adapted to fitinto said bore;

second resilient annular wiping means on the lower portion of saidmandrel having an outside diameter at least as great as the insidediameter of said lower section for wiping engagement therewith;

second annular spacing means on said mandrel be tween said second wipingmeans;

a pointed retaining nut aflixed to the lower end of said mandrel forholding said second wiping means and said second spacing means on saidmandrel; and

shear pin means holding said mandrel in said body member.

2. For use in a well installation including a well pipe having an uppersection with a first inside diameter, and a lower section with a secondsmaller inside diameter, a pipe wiper comprising:

an elongated body member having a bore extending therethrough, andincluding an outwardly extending flange at one end thereof, the diameterof said bore being less than the inside diameter of said lower section;

a check valve at the upper end of said bore for o posing passage offluids up through said bore;

first annular resilient wiping means afiixed to the exterior of saidbody member and having an outside diameter slightly greater than theinside diameter of said upper section of said well pipe;

an elongated mandrel having at least a portion adapted to fit into saidbore;

resilient wiping means alfixed to said mandrel having an outsidediameter at least as great as the inside diameter of said lower sectionfor wiping engagement therewith; and

shear pin means holding said mandrel in said body member.

3. For use in a well installation including a well pipe having an uppersection with a first inside diameter, and a lower section with a .secondsmaller inside diameter, a pipe wiper comprising:

an elongated body member having a bore extending therethrough, andincluding an outwardly extending flange at one end thereof, the diameterof said bore being less than the inside diameter of said lower section;

a check valve at the upper end of said bore for opposing passage offluids up through said bore;

first annular resilient wiping means affixed to the exterior of saidbody member and having an outside diameter slightly greater than theinside diameter of said upper section of said well pipe;

an elongated mandrel releasably held within the bore of said body memberhaving at least a portion adapted to fit into said bore; and

second resilient annular wiping means afiixed to said mandrel and havingan outside diameter at least as great as the inside diameter of saidlower section for wiping engagement therewith.

References Cited in the file of this patent UNITED STATES PATENTS1,793,644 Segelhorst et al. Feb. 24, 1931 2,188,959 Schaer Feb. 6, 19402,257,080 Turner Sept. 23, 1941 2,601,614 Johnson June 24, 19522,762,439 Pomeroy Sept. 11, 1956

